All-optical control of memristor based on oxide heterojunction and preparation method thereof

Abstract

The application discloses an all-optical control memristor based on an oxide heterojunction and a preparation method thereof, and belongs to the technical field of optoelectronic functional materials and devices. The all-optical control memristor disclosed by the application comprises, from bottom to top, a substrate, a bottom electrode layer, an intermediate oxide heterojunction layer and a transparent electrode layer which are stacked in sequence; the intermediate oxide heterojunction layer is composed of a Zn2TiO4 thin film layer and a ZnO thin film layer; and the Zn2TiO4 thin film layer is located above or below the ZnO thin film layer. By adopting the Zn2TiO4 thin film layer and the ZnO thin film layer to form the intermediate oxide heterojunction layer, a II-type heterojunction with a certain barrier width is formed, the directional transfer ability of photoelectrons is increased, and thus the all-optical regulation performance of the conductive state is effectively improved. Compared with a single-layer oxide, the all-optical control memristor based on the double-layer oxide heterojunction disclosed by the application has a larger working window and better stability.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic functional materials and devices technology, specifically relating to an all-optically controlled memristor based on an oxide heterojunction and its fabrication method. Background Technology

[0002] As artificial intelligence applications become increasingly complex and data volumes continue to expand, higher demands are placed on the underlying computing architecture: it must meet the computational power requirements for high-speed processing of massive amounts of data, be equipped with compatible large-scale storage capacity, and achieve these goals within a limited energy budget, i.e., achieve a higher energy efficiency ratio. However, the traditional von Neumann computing architecture, due to the physical separation of storage and computing units, leads to frequent data migration between the two, resulting in significant additional latency and energy consumption, and severely restricting overall computing efficiency, becoming a key physical bottleneck restricting the continuous improvement of computing performance. Therefore, neuromorphic computing, drawing on the in-memory computing, parallel processing, and low power consumption characteristics of the biological brain, is considered a potential new paradigm for overcoming these bottlenecks. Memristors, as two-terminal devices, have the characteristics of simple structure, easy high-density integration, and non-volatility, and can efficiently simulate biological synaptic functions, thus becoming a key unit for building neuromorphic hardware.

[0003] However, traditional electrically controlled memristors still have limitations. Electrical signals cause changes in the material's microstructure and generate significant Joule heating, leading to deterioration in device stability and high power consumption, severely restricting the practical application of memristors. Compared to electrical signals, optical signals offer advantages such as high parallelism, high speed, high bandwidth, and low crosstalk, and can achieve non-destructive or low-destructive operation on the device. Therefore, the development of opto-memristors has attracted widespread attention from researchers. Furthermore, opto-memristors can directly sense and process optical signals, and the processing results can be directly stored in the device, potentially enabling integrated sensing, storage, and computing functions at the device level. However, due to the photoelectric effect in semiconductors, illumination generally only increases the memristor's conductance, making it difficult to achieve photo-induced conductance reduction. Therefore, most reported opto-memristors require photoelectric coordination to achieve reversible control of the device's conductance. In this approach, the complexity and additional power consumption brought about by photoelectric signal conversion pose certain challenges to practical applications.

[0004] To fundamentally address these issues, the concept of fully optically controllable memristors was proposed, attracting widespread attention from researchers. These devices can achieve reversible control of conductance using only optical signals of different wavelengths and powers, providing a highly promising solution for neuromorphic computing. Researchers have developed fully optically controllable memristors based on various material systems, including oxide materials, low-dimensional materials, perovskite materials, organic materials, and ferroelectric materials. However, new materials such as low-dimensional and perovskite materials face challenges such as difficulty in large-area fabrication, poor stability, and susceptibility to environmental influences, limiting their development. Oxide materials, due to their advantages such as good compatibility with CMOS processes, stable physicochemical properties, low fabrication costs, ease of large-scale integration, and easy manipulation of defects (such as oxygen vacancies), have led to the rapid development of oxide-based fully optically controllable memristors. Common oxide materials include ZnO, InGaZnO, NiO, Ga2O3, TiO2, and Zn2SnO4. However, fully optically controllable memristors based on oxide materials also have some limitations. For example, patent CN 117881273 A discloses a fully optically controlled memristor based on a single-layer ZnO. Due to the limited directional transfer capability of photoelectrons in a single-layer oxide, the reduction in photoinduced conductance is relatively small, approximately 21.4%. Patent CN 111525027 A designs a fully optically controlled memristor based on a double-layer InGaZnO composite structure, with a reduction in photoinduced conductance of approximately 18.1%. Patent CN 114464732 B proposes a ZnO / MoO... x The heterojunction-based fully optically controlled memristor, through the design of the heterojunction structure, significantly improves the reduction in optically induced conductance by approximately 63.14%. However, its narrow wavelength response range, limited to only 500-560 nm, restricts its applications. Therefore, it is necessary to further increase the reduction in optically induced conductance and broaden the wavelength response range. Summary of the Invention

[0005] The purpose of this invention is to provide an all-optically controlled memristor based on an oxide heterojunction and its fabrication method, so as to solve the technical problem of poor all-optical control performance of existing optically controlled memristors.

[0006] To achieve the above objectives, the present invention employs the following technical solution: This invention discloses a fully optically controlled memristor based on an oxide heterojunction, wherein the fully optically controlled memristor comprises, from bottom to top, a series of stacked components: Substrate, bottom electrode layer, intermediate oxide heterojunction layer, and transparent electrode layer; The intermediate oxide heterojunction layer is composed of a Zn2TiO4 thin film layer and a ZnO thin film layer; The Zn2TiO4 thin film layer is located above or below the ZnO thin film layer.

[0007] Furthermore, the thickness of the Zn2TiO4 thin film layer and the ZnO thin film layer is 10~100 nm.

[0008] Furthermore, the bottom electrode layer is a metal electrode or a compound electrode; The metal electrode is Au, Pt, Cu, Ag, or Ti; the compound electrode is ITO or AZO.

[0009] Furthermore, the transparent electrode layer (1) is an ultrathin metal layer, a transparent conductive compound layer, or a composite electrode composed of an ultrathin metal layer and a transparent conductive compound layer; The ultrathin metal layer is Au, Pt, Cu, Ag or Ti; the transparent conductive compound layer is ITO or AZO; the thickness of the ultrathin metal layer is <30 nm.

[0010] Furthermore, the substrate is one or more of silicon, glass, single-crystal oxide, polymer flexible substrate, and two-dimensional crystal material.

[0011] Furthermore, the conductance of the all-optically controlled memristor based on oxide heterojunction is controlled by ultraviolet, visible or near-infrared light; when irradiated by ultraviolet and visible light, the conductance increases, and the wavelength of the optical signal is 260~450 nm.

[0012] Furthermore, when irradiated by visible and near-infrared light, the conductivity is reduced, and the wavelength of the optical signal is 420~1000 nm.

[0013] This invention also discloses a method for fabricating an all-optically controlled memristor based on an oxide heterojunction, characterized by comprising the following steps: A bottom electrode layer, an intermediate oxide heterojunction layer, and a transparent electrode layer are sequentially fabricated from bottom to top on the substrate surface using a film deposition method to obtain an all-optically controlled memristor based on an oxide heterojunction.

[0014] Furthermore, after preparing the intermediate oxide heterojunction layer, an annealing treatment is performed; The annealing process is carried out at a temperature of 400~700 ℃ for a time of 0.1~10 h.

[0015] Furthermore, the coating method is physical vapor deposition or chemical vapor deposition.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses an all-optically controllable memristor based on an oxide heterojunction. By employing a Zn₂TiO₄ thin film layer and a ZnO thin film layer to form an intermediate oxide heterojunction layer, a type II heterojunction with a certain barrier width is formed. This type II heterojunction can use ultraviolet and visible light to adjust the barrier width, thereby increasing or decreasing conductivity and further improving the device's light responsivity. Compared to previously disclosed all-optically controllable memristors, the heterojunction structure proposed in this invention significantly widens the device's operating window, effectively improving all-optical control performance. It achieves a wide range of all-optically tunable conductivity and long-term device stability, laying a superior device foundation for applications in neuromorphic computing and artificial vision.

[0017] Furthermore, this invention prepares Zn₂TiO₄ and ZnO thin films using physical vapor deposition in a pure argon atmosphere. The high oxygen vacancy concentration in the thin films introduces abundant defect state energy levels, enabling sub-bandgap absorption and broadening the spectral response range. Furthermore, coupling the oxygen vacancy design with this type II heterojunction effectively broadens the device's optical response band (UV→Vis→Near-infrared) and significantly enhances its photoresponsivity. Moreover, the spinel-structured Zn₂TiO₄ possesses excellent chemical and thermal stability, effectively constraining and stabilizing the distribution and migration of oxygen vacancies. This is one of the core solutions for realizing a wide-spectrum, high-performance, and highly stable in-memory computing device.

[0018] The present invention also discloses the above-mentioned method for fabricating an all-optically controlled memristor based on an oxide heterojunction. This method uses magnetron sputtering, which can achieve large-area fabrication, good uniformity, and CMOS compatibility under high performance conditions. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of an existing single-layer oxide memristor. Wherein: A - electrode layer; B - ZnO layer; C - bottom electrode layer; D - bottom substrate; Figure 2 This is a schematic diagram of the structure of an all-optically controlled memristor based on an oxide heterojunction constructed according to the present invention; Wherein: 1-transparent electrode layer; 2-ZnO thin film layer; 3-Zn2TiO4 thin film layer; 4-bottom electrode layer; 5-substrate; Figure 3 This is a flowchart illustrating the fabrication process of the fully optically controlled memristor based on an oxide heterojunction according to the present invention. Figure 4 The photoelectric response of the oxide heterojunction fully optically controlled memristor prepared in Example 1 is increased to improve the conductivity, wherein the optical signal uses light with a wavelength of 350 nm. Figure 5The photoelectric response of the oxide heterojunction fully optically controlled memristor prepared in Example 1 is reduced by the conductivity, wherein the optical signal uses light with a wavelength of 450 nm. Figure 6 The photoelectric response of the oxide heterojunction fully optically controlled memristor prepared in Example 1 is reduced by the conductivity, wherein the optical signal uses light with a wavelength of 900 nm; Figure 7 The photoresponse of the oxide heterojunction fully optically controlled memristor prepared in Example 1, with reduced conductivity after 7 months of storage, wherein the optical signal uses light with a wavelength of 450 nm; Figure 8 To increase the photoelectric response of the oxide heterojunction fully optically controlled memristor prepared in Example 2, wherein the optical signal uses light with a wavelength of 350 nm. Figure 9 The photoelectric response of the oxide heterojunction fully optically controlled memristor prepared in Example 2 is reduced by decreasing conductivity, wherein the optical signal uses light with a wavelength of 450 nm. Figure 10 To increase the photoelectric response of the oxide heterojunction fully optically controlled memristor prepared in Example 3, wherein the optical signal uses light with a wavelength of 350 nm. Figure 11 The photoelectric response of the oxide heterojunction fully optically controlled memristor prepared in Example 3 is reduced by decreasing the conductivity, wherein the optical signal uses light with a wavelength of 450 nm. Figure 12 To increase the photoelectric response of the monolayer oxide fully optically controlled memristor prepared in Comparative Example 1, wherein the optical signal uses light with a wavelength of 350 nm; Figure 13 The photoelectric response of the monolayer oxide fully optically controlled memristor prepared for Comparative Example 1 is reduced to decrease the conductivity, wherein the optical signal uses light with a wavelength of 450 nm. Detailed Implementation

[0020] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0021] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0022] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0023] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0024] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0025] This invention provides a fully optically controlled memristor based on an oxide heterojunction. Its stacked structure, from bottom to top, consists of: a substrate 5, a bottom electrode layer 4, an intermediate oxide heterojunction layer, and a transparent electrode layer 1. This invention introduces abundant defect state energy levels through oxygen vacancies in the Zn₂TiO₄ and ZnO thin film layers, achieving sub-bandgap absorption and broadening the spectral response range. Furthermore, coupling the oxygen vacancy design with this type II heterojunction effectively broadens the device's optical response band (UV→Vis→NIR) and significantly enhances its photoresponsivity. Moreover, the spinel structure of Zn₂TiO₄ exhibits good chemical and thermal stability, effectively constraining and stabilizing the distribution and migration of oxygen vacancies. The fully optically controlled memristor based on the oxide heterojunction can achieve reversible conductance control with only optical signals of different wavelengths and powers.

[0026] Preferably, the thickness of the Zn2TiO4 thin film layer 3 and the ZnO thin film layer 2 is 10~100 nm.

[0027] Preferably, the substrate 5 can be a rigid or flexible material, specifically including one or more of silicon or glass, single-crystal oxide, polymer flexible substrate, and two-dimensional crystal material.

[0028] More preferably, considering compatibility with CMOS processes and applications in the field of information technology, the substrate 5 is selected from rigid silicon-based materials; further preferably, it is a commercially available platinum-plated silicon wafer; even more preferably, the structure of the substrate 5 from bottom to top is: Si / SiO2 (290nm) / Ti (50nm) / Pt (200nm), wherein Ti is used as an adhesion layer to enhance the bonding force between SiO2 and Pt.

[0029] Preferably, the bottom electrode layer 4 is made of Pt from the substrate described above, and has a thickness of 200 nm.

[0030] Preferably, the Zn2TiO4 thin film layer 3 is made of Zn2TiO4 with a thickness of 10~100 nm, and more preferably 30 nm.

[0031] Preferably, the ZnO thin film layer 2 is made of ZnO with a wavelength of 10-100 nm, and more preferably 50 nm.

[0032] Preferably, the Zn2TiO4 thin film layer 3 is located above or below the ZnO thin film layer 2; more preferably below.

[0033] Preferably, the transparent electrode layer 1 is selected from one or more of the following: an ultrathin metal layer: Au, Pt, Cu, Ag or Ti, or a transparent conductive compound layer: ITO or AZO, or a composite electrode composed of an ultrathin metal layer and a transparent conductive compound layer; more preferably, it is 10 nm Pt and 30 nm ITO, and a Pt film of a certain thickness can meet the transmittance requirements of the wavelength band used in this invention. Preferably, when the photoinduced conductivity increases, the optical signal is ultraviolet light or visible light with a wavelength of 260~450 nm; more preferably, it is 350 nm ultraviolet light.

[0034] Preferably, when the photoinduced conductivity is reduced, the optical signal is visible light and near-infrared light with a wavelength of 420~1000 nm; more preferably, it is 450 nm blue light.

[0035] This invention also discloses a method for fabricating the above-mentioned fully optically controlled memristor based on an oxide heterojunction, comprising the following steps: A bottom electrode layer 4, an intermediate oxide heterojunction layer, and a transparent electrode layer 1 are sequentially prepared from bottom to top on the surface of substrate 5 using a film deposition method to obtain an all-optically controlled memristor based on an oxide heterojunction.

[0036] After preparing the intermediate oxide heterojunction layer, an annealing treatment is performed; the annealing treatment temperature is 400~700 ℃ and the time is 0.1~10 h.

[0037] More specifically, such as Figure 3 As shown, it includes the following steps: S1: The commercial platinum-plated silicon wafer is ultrasonically cleaned with acetone, ethanol and deionized water for 6-15 minutes in sequence, and then dried with a nitrogen gun to serve as substrate 5. S2: A Zn2TiO4 thin film is deposited on a commercially platinum-plated silicon wafer to obtain Zn2TiO4 thin film layer 3; S3: Deposit a ZnO film on a Zn2TiO4 film to obtain ZnO film layer 2, and then perform annealing treatment; S4: Deposit Pt, ITO, or Pt / ITO electrodes on the prepared intermediate dielectric layer to form transparent electrode layer 1, thereby obtaining an all-optically controlled memristor based on an oxide heterojunction.

[0038] The growth parameters for the Zn2TiO4 thin film are as follows: the film is sputtered using a Zn2TiO4 target at a power of 70W and a working pressure of 0.5 Pa under a pure argon atmosphere at room temperature; the growth parameters for the ZnO thin film are as follows: the film is sputtered using a ZnO target at a power of 60W and a working pressure of 0.5 Pa under a pure argon atmosphere at room temperature to obtain the intermediate dielectric layer; and the film is then placed in an annealing furnace and annealed in air at a temperature of 500 ℃ or 600 ℃ for 1 h.

[0039] The Pt growth parameters are as follows: a Pt target is used to sputter a thin film at a power of 60 W and a working pressure of 1 Pa in a pure argon atmosphere at room temperature; the ITO growth parameters are as follows: an ITO target is used to sputter a thin film at a power of 65 W and a working pressure of 0.6 Pa in a mixed argon-oxygen atmosphere at room temperature.

[0040] In steps S2-S4, the method for depositing thin films is magnetron sputtering.

[0041] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0042] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0043] Figure 1 The diagram shows an existing monolayer oxide fully optically controlled memristor structure, whose stacked structure from bottom to top is as follows: bottom substrate D, bottom electrode layer C, ZnO layer B, and electrode layer A; Figure 2The diagram shows the structure of the all-optically controlled memristor based on an oxide heterojunction constructed according to the present invention. Its stacked structure, from bottom to top, consists of: substrate 5, bottom electrode layer 4, Zn₂TiO₄ thin film layer 3, ZnO thin film layer 2, and transparent electrode layer 1. In the examples described below, light is incident through the transparent electrode layer 1.

[0044] Example 1 A fully optically controlled memristor based on an oxide heterojunction, the stacked structure of which, from bottom to top, is as follows: The structure comprises a substrate 5, a bottom electrode layer 4, a Zn2TiO4 thin film layer 3, a ZnO thin film layer 2, and a transparent electrode layer 1; wherein the substrate 5 is a commercially available platinum-plated silicon wafer; the Pt in the substrate 5 serves as the bottom electrode layer 4 with a thickness of 200 nm; the Zn2TiO4 thin film layer 3 serves as an oxide layer with a thickness of 30 nm; the ZnO thin film layer 2 serves as an oxide layer with a thickness of 50 nm; and the transparent electrode layer 1 is a Pt layer with a thickness of 10 nm. The fabrication method of the fully optically controlled memristor based on oxide heterojunction consists of steps S1-S4: S1: Commercial platinum-plated silicon wafers were ultrasonically cleaned with acetone, ethanol and deionized water for 12 min in sequence, and then dried with a nitrogen gun to serve as substrate 5. S2: A Zn2TiO4 thin film was deposited on a commercially available platinum-plated silicon wafer using magnetron sputtering to obtain Zn2TiO4 thin film layer 3; the growth parameters were: the thin film was sputtered using a Zn2TiO4 target at 70W power and 0.5Pa working pressure under room temperature and pure argon atmosphere. S3: A ZnO film was deposited on a Zn2TiO4 film to obtain ZnO film layer 2, and then annealed. The growth parameters were as follows: the film was sputtered using a ZnO target at a power of 60W and a working pressure of 0.5Pa at room temperature and in a pure argon atmosphere to obtain an intermediate dielectric layer. The film was then placed in an annealing furnace and annealed at 600℃ for 1 hour in an air environment. S4: Deposit a Pt electrode on the prepared intermediate dielectric layer to form a transparent electrode layer 1, and obtain an all-optically controlled memristor based on an oxide heterojunction; Pt growth parameters are: sputter thin film using a Pt target at 60W power and 1Pa working pressure under room temperature and pure argon atmosphere.

[0045] To quantify the photoresponse amplitude of a device, this invention introduces a formula for calculating photoresponsivity. The set index reflects the magnitude of the photoinduced conductivity enhancement. A larger set index indicates a greater photoinduced conductivity enhancement, and vice versa. The specific calculation formula is as follows: =| 1 2 / 1|×100%; in, I 1 indicates the initial current value of the device. I 2 represents light The current value after that; The reset index reflects the magnitude of the decrease in photoinduced conductivity of a device: a larger index value indicates a greater decrease in photoinduced conductivity, and vice versa. The specific calculation formula is as follows: =| 1 2 / 1|×100%; in, I 1 indicates the initial current value of the device. I 2 represents light The current value after that.

[0046] like Figure 4 As shown, 350 nm (optical power density of 40 μW / cm²) was used. 2) Ultraviolet light was continuously irradiated on the all-optically controlled memristor based on oxide heterojunction in this embodiment for 15 s. Under a read voltage of 0.1 V, the device current gradually increased, that is, from a low conductivity state to a high conductivity state. After the light was removed, the conductivity level remained above the initial conductivity state for a long time, showing a photoelectric response with photoinduced conductivity increase. The calculated SET index was 533.14%. This can be explained as follows: (1) The intrinsic excitation based on oxide under ultraviolet light will generate a large number of photogenerated carriers; (2) At the same time, neutral oxygen vacancies in oxide ionize to generate charged oxygen vacancies and electrons. The increase in the number of charged oxygen vacancies leads to a narrowing of the barrier width of Zn2TiO4 / ZnO heterojunction, thereby increasing the device conductivity; (3) The built-in electric field formed at the interface separates the generated electrons and holes, resulting in a significant reduction in the recombination probability, thereby showing excellent non-volatility of the device conductivity.

[0047] like Figure 5 As shown, 450 nm (optical power density of 60 μW / cm²) was used. 2 Blue light was continuously irradiated onto the all-optically controlled memristor based on an oxide heterojunction in this embodiment for 120 seconds. At a read voltage of 0.1 V, the device current gradually decreased, i.e., from a high conductivity state to a low conductivity state. After the light was removed, the conductivity level remained below the initial conductivity state for a long time, exhibiting a photoelectric response of light-induced conductivity reduction. The calculated RESET index was 49.80%. This can be explained as follows: under blue light irradiation, electrons in the potential well are excited, promoting the recombination of charged oxygen vacancies and electrons, resulting in a widening of the Zn2TiO4 / ZnO heterojunction barrier width and a decrease in device conductivity.

[0048] like Figure 6 As shown, 900 nm (optical power density of 60 μW / cm²) was used. 2 Near-infrared light was continuously irradiated onto the all-optically controlled memristor based on oxide heterojunction in this embodiment for 120 s. At a read voltage of 0.1 V, the device current gradually decreased, that is, from a high conductivity state to a low conductivity state. After the light was removed, the conductivity level remained below the initial conductivity state for a long time, showing a photoelectric response of light-induced conductivity reduction. The calculated RESET index was 23.08%.

[0049] Figure 7 The device in this embodiment was fabricated and stored for 7 months before being used at 450 nm (optical power density of 60 μW / cm²). 2 When the device is continuously irradiated with blue light for 120 seconds, its conductivity level remains at the initial conductivity state for a long time after the light is removed. The calculated RESET index is 44.98%, with no significant decrease, indicating that the device exhibits long-term stability.

[0050] Example 2 A fully optically controlled memristor based on an oxide heterojunction, the stacked structure of which, from bottom to top, is as follows: The structure comprises a substrate 5, a bottom electrode layer 4, a Zn2TiO4 thin film layer 3, a ZnO thin film layer 2, and a transparent electrode layer 1; wherein the substrate 5 is a commercially available platinum-plated silicon wafer; the Pt in the substrate 5 serves as the bottom electrode layer 4 with a thickness of 200 nm; the Zn2TiO4 thin film layer 3 serves as an oxide layer with a thickness of 30 nm; the ZnO thin film layer 2 serves as an oxide layer with a thickness of 50 nm; and the transparent electrode layer 1 is ITO with a thickness of 30 nm. The fabrication method of the fully optically controlled memristor based on oxide heterojunction consists of steps S1-S4: S1: Commercial platinum-plated silicon wafers were ultrasonically cleaned with acetone, ethanol and deionized water for 12 min in sequence, and then dried with a nitrogen gun to serve as substrate 5. S2: A Zn2TiO4 thin film was deposited on a commercially available platinum-plated silicon wafer using magnetron sputtering to obtain Zn2TiO4 thin film layer 3; the growth parameters were: the thin film was sputtered using a Zn2TiO4 target at 70W power and 0.5Pa working pressure under room temperature and pure argon atmosphere. S3: A ZnO film was deposited on a Zn2TiO4 film to obtain ZnO film layer 2, and then annealed. The growth parameters were as follows: the film was sputtered using a ZnO target at a power of 60W and a working pressure of 0.5Pa at room temperature and in a pure argon atmosphere to obtain an intermediate dielectric layer. The film was then placed in an annealing furnace and annealed at 600℃ for 1 hour in an air environment. S4: Deposit an ITO electrode on the prepared intermediate dielectric layer to form a transparent electrode layer 1, thereby obtaining an all-optically controlled memristor based on an oxide heterojunction; The growth parameters of ITO are: sputtering thin films using an ITO target at 65W power and 0.6Pa working pressure in an environment of room temperature and argon-oxygen mixture.

[0051] like Figure 8 As shown, 350 nm (optical power density of 40 μW / cm²) was used. 2 When the device in this embodiment is continuously irradiated with ultraviolet light for 15 seconds, the device current gradually increases at a read voltage of 0.1V, that is, from a low conductivity state to a high conductivity state. After the light is removed, the conductivity level remains above the initial conductivity state for a long time, showing a photoelectric response of light-induced conductivity increase. The calculated SET index is 410.12%. like Figure 9 As shown, 450 nm (optical power density of 60 μW / cm²) was used. 2When the device in this embodiment is continuously irradiated with blue light for 120 seconds, the device current gradually decreases at a read voltage of 0.1V, i.e., from a high conductivity state to a low conductivity state. After the light is removed, the conductivity level remains below the initial conductivity state for a long time, exhibiting a photoelectric response of light-induced conductivity reduction. The calculated RESET index is 21.48%.

[0052] Example 3 A fully optically controlled memristor based on an oxide heterojunction, the stacked structure of which, from bottom to top, is as follows: The structure comprises a substrate 5, a bottom electrode layer 4, a Zn2TiO4 thin film layer 3, a ZnO thin film layer 2, and a transparent electrode layer 1; wherein the substrate 5 is a commercially available platinum-plated silicon wafer; the Pt in the substrate 5 serves as the bottom electrode layer 4 with a thickness of 200 nm; the Zn2TiO4 thin film layer 3 serves as an oxide layer with a thickness of 30 nm; the ZnO thin film layer 2 serves as an oxide layer with a thickness of 50 nm; and the transparent electrode layer 1 is a Pt layer with a thickness of 10 nm. The fabrication method of the fully optically controlled memristor based on oxide heterojunction consists of steps S1-S4: S1: Commercial platinum-plated silicon wafers were ultrasonically cleaned with acetone, ethanol and deionized water for 12 min in sequence, and then dried with a nitrogen gun to serve as substrate 5. S2: A Zn2TiO4 thin film was deposited on a commercially available platinum-plated silicon wafer using magnetron sputtering to obtain Zn2TiO4 thin film layer 3; the growth parameters were: the thin film was sputtered using a Zn2TiO4 target at 70W power and 0.5Pa working pressure under room temperature and pure argon atmosphere. S3: A ZnO film was deposited on a Zn2TiO4 film to obtain ZnO film layer 2, and then annealed. The growth parameters were as follows: the film was sputtered using a ZnO target at a power of 60W and a working pressure of 0.5Pa at room temperature and in a pure argon atmosphere to obtain an intermediate dielectric layer. The film was then placed in an annealing furnace and annealed at 500℃ for 1 hour in an air environment. S4: Deposit a Pt electrode on the prepared intermediate dielectric layer to form a transparent electrode layer 1, and obtain an all-optically controlled memristor based on an oxide heterojunction; Pt growth parameters are: sputter thin film using a Pt target at 60W power and 1Pa working pressure under room temperature and pure argon atmosphere.

[0053] like Figure 10 As shown, 350 nm (optical power density of 40 μW / cm²) was used. 2When the device in this embodiment is continuously irradiated with ultraviolet light for 15 seconds, the device current gradually increases at a read voltage of 0.1V, that is, from a low conductivity state to a high conductivity state. After the light is removed, the conductivity level remains above the initial conductivity state for a long time, showing a photoelectric response of light-induced conductivity increase. The calculated SET index is 201.50%. like Figure 11 As shown, 450 nm (optical power density of 60 μW / cm²) was used. 2 When the device in this embodiment is continuously irradiated with blue light for 120 seconds, the device current gradually decreases at a read voltage of 0.1V, i.e., from a high conductivity state to a low conductivity state. After the light is removed, the conductivity level remains below the initial conductivity state for a long time, exhibiting a photoelectric response of light-induced conductivity reduction. The calculated RESET index is 21.26%.

[0054] Comparative Example 1 A monolayer oxide fully optically controlled memristor is disclosed. Compared with Example 1, the intermediate dielectric layer of this comparative example is a ZnO oxide layer. The preparation method of this monolayer oxide fully optically controlled memristor is the above-described steps S1-S4, except that the preparation of the Zn2TiO4 thin film is removed.

[0055] like Figure 12 As shown, 350 nm (optical power density of 40 μW / cm²) was used. 2 When the monolayer device in the comparative example was continuously irradiated with ultraviolet light for 15 seconds, the device current gradually increased at a read voltage of 0.1V, that is, from a low conductivity state to a high conductivity state. After the light was removed, the conductivity level remained above the initial conductivity state for a long time, showing a photoelectric response of light-induced conductivity increase. The calculated SET index was 30.12%. like Figure 13 As shown, 450 nm (optical power density of 60 μW / cm²) was used. 2 When the device is continuously irradiated with blue light for 120 seconds, the device current gradually decreases at a read voltage of 0.1V, i.e., from a high conductivity state to a low conductivity state. After the light is removed, the conductivity level remains below the initial conductivity state for a long time, exhibiting a photoelectric response of light-induced conductivity reduction. The calculated RESETindex is 13.79%.

[0056] In summary, compared with single-layer oxide memristors, the all-optically controlled memristor based on oxide heterojunction provided by this invention, under optimal conditions, increases the SET index from 30.12% to 533.14% and the RESET index from 13.79% to 49.80%, significantly improving the adjustable conductance range; under all-optical conditions, it achieves wide-range tunable conductance, good non-volatility, and long-term device stability.

[0057] The fully optically controlled memristor based on oxide heterojunction disclosed in this invention can overcome the limitations of traditional electrically controlled memristors. By rationally designing the oxygen vacancy concentration and spatial distribution and coupling it with the heterojunction bandgap, it can achieve advantages such as wide spectrum, high responsivity, and non-volatility. Furthermore, the optical power density used is very low, which greatly reduces energy consumption. The oxide used has good chemical and thermal stability, which is beneficial for its practical application in fields such as neuromorphic computing and artificial intelligence hardware.

[0058] In summary, the all-optical controllable memristor technology based on oxide heterojunction disclosed in this invention addresses the shortcomings of existing optically controllable memristors in terms of poor all-optical control performance. Through a comprehensive synergy of innovative structural design, precise material selection, a wide-band bidirectional control mechanism, and optimized fabrication processes, it achieves a systematic breakthrough in control performance, demonstrating significant advantages and a logically closed loop. In terms of structural design, the innovative solution employs an intermediate oxide heterojunction layer composed of Zn₂TiO₄ and ZnO thin film layers. The synergistic effect of these two oxide materials constructs a unique interfacial energy level structure. Compared to traditional single oxide or homogeneous thin film structures, the built-in electric field formed at the heterojunction interface can effectively control the separation, transport, and recombination efficiency of photogenerated carriers, providing a core physical basis for all-optical control. Simultaneously, both Zn₂TiO₄ and ZnO possess excellent photoresponse characteristics and stable chemical properties. Their combination retains the high absorption of ultraviolet-visible light by ZnO's wide bandgap material. The coefficient, and with the help of the inverse spinel structure of Zn2TiO4, since the oxygen vacancy energy levels introduced in Zn2TiO4 are deeper and more abundant, while the oxygen vacancy energy levels introduced in ZnO are relatively shallower; when Zn2TiO4 and ZnO form a heterojunction, their energy bands will be staggered, and the defect state energy levels will be distributed at different depths, thus broadening the response range in the visible to near-infrared light band; the wide-band coverage and bidirectional function realization of all-optical control significantly breaks through the bottleneck of the single control method and limited response band of the existing optically controlled memristor. The scheme uses ultraviolet light (260~450) Conductivity is increased using visible light (420-1000 nm) and decreased using visible and near-infrared light (420-1000 nm). This bidirectional control function covers commonly used wavelengths from ultraviolet to near-infrared, requiring no electrical signal assistance and achieving true full optical control. It adapts to the multi-band control needs of various scenarios such as neuromorphic computing and optical storage. This wide-band bidirectional control capability stems from the bandgap engineering design of the oxide heterojunction. The complementary band gaps of Zn2TiO4 and ZnO allow the heterojunction to flexibly control the interface carrier concentration and transport characteristics under different wavelengths of light, achieving precise switching between excitation and suppression. This solves the problem of traditional optically controlled memristors relying on single-band, single-function control and having poor adaptability. Optimized fabrication processes further ensure the stability and consistency of the control performance. The scheme uses mature coating technologies such as physical vapor deposition or chemical vapor deposition, which can precisely control the thickness uniformity and microstructure of each thin film layer, avoiding fluctuations in control performance caused by film defects. Annealing treatment (400-700 nm) after the preparation of the intermediate oxide heterojunction layer... (℃, 0.1~10 h), can effectively eliminate internal stress in the film layer, improve crystallization quality, optimize heterojunction interface characteristics, enhance carrier transport efficiency and structural stability, and solve problems such as low film layer crystallinity and many interface defects in traditional preparation processes, resulting in poor control repeatability and short lifetime. The whole preparation process is simple and highly compatible, which not only ensures the consistency of device performance, but also lays the foundation for large-scale production.

[0059] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A fully optically controlled memristor based on an oxide heterojunction, characterized in that, The fully optically controlled memristor comprises, from bottom to top, a series of stacked components: Substrate (5), bottom electrode layer (4), intermediate oxide heterojunction layer and transparent electrode layer (1); The intermediate oxide heterojunction layer is composed of a Zn2TiO4 thin film layer (3) and a ZnO thin film layer (2); The Zn2TiO4 thin film layer (3) is located above or below the ZnO thin film layer (2).

2. A fully optically controlled memristor based on an oxide heterojunction according to claim 1, characterized in that, The thickness of the Zn2TiO4 thin film layer (3) and the ZnO thin film layer (2) is 10~100 nm.

3. The all-optically controlled memristor based on an oxide heterojunction according to claim 1, characterized in that, The bottom electrode layer (4) is a metal electrode or a compound electrode; The metal electrode is Au, Pt, Cu, Ag, or Ti; the compound electrode is ITO or AZO.

4. The all-optically controlled memristor based on an oxide heterojunction according to claim 1, characterized in that, The transparent electrode layer (1) is an ultrathin metal layer, a transparent conductive compound layer, or a composite electrode composed of an ultrathin metal layer and a transparent conductive compound layer; The ultrathin metal layer is Au, Pt, Cu, Ag or Ti; the transparent conductive compound layer is ITO or AZO; the thickness of the ultrathin metal layer is <30 nm.

5. A fully optically controlled memristor based on an oxide heterojunction according to claim 1, characterized in that, The substrate (5) is one or more of silicon, glass, single crystal oxide, polymer flexible substrate and two-dimensional crystal material.

6. A fully optically controlled memristor based on an oxide heterojunction according to claim 1, characterized in that, The conductance of the all-optically controlled memristor based on oxide heterojunction is controlled by ultraviolet, visible or near-infrared light; when irradiated by ultraviolet and visible light, the conductance increases, and the wavelength of the optical signal is 260~450 nm.

7. A fully optically controlled memristor based on an oxide heterojunction according to claim 6, characterized in that, When irradiated by visible and near-infrared light, the conductivity is reduced, and the wavelength of the optical signal is 420~1000 nm.

8. A method for fabricating an all-optically controlled memristor based on an oxide heterojunction as described in any one of claims 1 to 7, characterized in that, Includes the following steps: A bottom electrode layer (4), an intermediate oxide heterojunction layer, and a transparent electrode layer (1) are sequentially prepared from bottom to top on the surface of the substrate (5) by a film deposition method to obtain an all-optically controlled memristor based on an oxide heterojunction.

9. The method for fabricating an all-optically controlled memristor based on an oxide heterojunction according to claim 8, characterized in that, After preparing the intermediate oxide heterojunction layer, annealing treatment is performed; The annealing temperature is 400~700 ℃, the annealing atmosphere is air, oxygen, argon or vacuum environment, and the annealing time is 0.1~10 h.

10. The method for fabricating an all-optically controlled memristor based on an oxide heterojunction according to claim 8, characterized in that, The coating method is physical vapor deposition, and the coating atmosphere is pure argon.

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